JPS6057442B2 - Photopolymerizable composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to photopolymerizable compositions comprising one or more substances that can be polymerized or cured by the action of acids, including Lewis acids.

Such substances are commonly referred to as acid-polymerizable substances or acid-curable substances, and may also be referred to as such herein below. According to the present invention, an acid polymerizable or acid curable substance selected from the group consisting of (a) formaldehyde condensates of urea, melamine and phenol; and N-vinylcarbazole;
b) at least one photosensitizer, the photosensitizer polymerizing or A photopolymerizable composition that can be cured: The photosensitizer has the following formula (1) (wherein A is sulfur, selenium or tellurium, and n is 1 or 2). R1, R2 and R3 may be the same or different and each is a hydrocarbon group, a substituted hydrocarbon group or a heterocyclic group; or two of R1, R2 and R3 and element A together form a heterocyclic structure, one other group R is a hydrocarbon group or a substituted hydrocarbon group, and XO is an anion derived from an acid capable of polymerizing or curing the substance (a) above. be.

) The photopolymerizable composition described above is provided.

Acid curable resins, such as phenolic resins (e.g. phenol/formaldehyde condensate) and amino acid resins (e.g. melamine/formaldehyde condensate, urea/formaldehyde condensate), when exposed to ultraviolet radiation, are It is well known that they can be cured by irradiation with ultraviolet, actinic or electromagnetic radiation in the presence of compounds that generate hydrogen (including Lewis acids).

Examples of compounds proposed for use in such compositions are halogen-containing compounds such as bromoform, carbon tetrabromide, ethane hexabromide, 2.5-dimethyl-tripromoacetophenone, 2. 2,2-trichloro-4″-tertiarybutylacetophenone, halomethylated benzophenone, α-methylolbenzoin sulfonic acid ester, and aryl diazonium salt of metal halide. Compounded in acid polymerizable or acid curable substances. The photosensitizing substances previously proposed for
or activated to release acids when exposed to electromagnetic radiation or actinic radiation containing a high proportion of ultraviolet radiation. However, it has been found that the previously proposed compositions are not satisfactory. The use of metal halide aryldiazonium salts polymerizes rapidly and is susceptible to premature gelation, resulting in compositions that cannot be stored satisfactorily even in the dark. In order to inhibit premature gelation of compositions containing metal halide aryl diazonium salts and to provide storage stability in the dark, it has been proposed to incorporate stabilizers and gelation inhibitors; This increases the cost of the composition and, furthermore, does not give entirely satisfactory results even under carefully controlled storage conditions. Furthermore, since the diazonium salts described above generate nitrogen gas when the composition is irradiated, the resulting cured material may contain undesirable air bubbles. Here,
When certain salts of sulfur, selenium or tellurium are incorporated as photosensitizers into acid-polymerizable and/or acid-curable materials,
It has been found that a photopolymerizable composition can be obtained which overcomes the drawbacks of the photopolymerizable compositions proposed so far.

Thus, for example, compositions containing this photosensitizer can be stored for long periods in the dark without appreciable gelation, and there is no need to supply a gelling control agent. Exposure of the photopolymerizable compositions of the present invention to radiation of the appropriate wavelength activates the photosensitizer and produces a catalytic species that can polymerize or cure the composition into a polymeric material.

The radiation may be ultraviolet or electron beam radiation, or may include wavelengths in the visible and ultraviolet regions of the spectrum.

The wavelength of the radiation may suitably be in the range, for example, from 200 to 600 TLμ. Preferably, the present invention uses radiation having a wavelength in the range of 200 to 400 TrLμ. Although sunlight may be used as the radiation, the optimal wavelength of radiation for any particular composition will be determined by the particular photomultiplier used in that composition. The optimal wavelength in any particular case can be easily determined by simple experimentation (eg, measurement of the electronic absorption spectrum of the photomultiplier).
In the photomultiplier of formula (1) above, the group R can be, for example, an alkyl, cycloalkyl, aryl, alkaryl or aralkyl group or a substituted derivative thereof.

Examples of substituents that may be present in the group R are halogen, alkoxy, -COOR-, -CORl-NO2, -NOl-
0H and -SH. When one or more radicals R in the photosensitizer are an alkyl group or a substituted alkyl group, it may contain 1 to 20 carbon atoms, preferably 2 to 6 carbon atoms. At least one, preferably at least two, of the radicals R are aryl or alkaryl groups or substituted aryl or alkaryl groups (in particular phenyl groups or phenyl group-containing groups such as -CH2COPh
; Ph is a phenyl group) is preferably used in the present invention. Preferred salts are sulfonium salts (ie, salts of formula (1) where A stands for sulfur). The anion Xn- in the photosensitizer may be, for example, a halogen-containing complex ion selected from ClO4- and metal halides.

The metal halide may be, for example, a polyhalide of boron, antimony, tin, silicon, phosphorous, arsenic, bismuth or iron. Examples of suitable anions are tetrafluoropolite (BF), hexachloroantimonate V (SbClJ), hexafluorantimonate V (SbFJ), hexachlorostanaate (SnC).
lJ-), hexafluorophosphate (PFJ),
These are hexafluoroarsenate (AsFJ), tetrachloropherete (FeCl7) and pentachlorobismacate (BiClV-). The ability of individual salts to polymerize or cure acid-polymerizable or acid-curable substances is
Strongly nucleophilic anions (e.g. halide ions), which are determined by the nucleophilicity of the anion and readily form covalent bonds with carbon atoms resulting in stable compounds, are commonly used in urea/formaldehyde and melamine/form. Polymerize or cure the aldehyde resin.

Examples of other ions of this type are CF3COO-\SO
3F-, ArSO3- (Ar' is an aromatic group, such as toluyl group), NO3- and picrate ion. The ability of an individual photosensitizer to cure a particular substance is dependent on the ability of the corresponding protic acid (i.e., a protic acid containing the same anion as the photosensitizer) to cure that substance. . Generally, if an acid polymerizes or cures the material, a corresponding salt containing the same anion can also polymerize or cure the material. Thus, the suitability of a particular salt for use with a particular acid-polymerizable or acid-curable material can generally be easily determined by simply mixing the material with the corresponding protic acid. It is believed that the photosensitizer releases acid when exposed to appropriate radiation, such as ultraviolet light.

The photosensitizers used in the present invention are normally solid at room temperature, and are typically present in an inert liquid diluent (i.e., a liquid diluent that is chemically inert to the components of the composition). It is added to an acid-polymerizable or acid-curable substance as a solution. Any inert liquid diluent in which the photosensitizer is sufficiently soluble may be used. Examples of suitable diluents are halogenated hydrocarbons (eg methylene chloride), ketones (eg acetone) and alcohols (eg ethanol). A low boiling point (e.g. 150'C) may be used to facilitate removal of the diluent from the composition.
It is preferable to use a liquid diluent as described below. The amount of diluent used is not critical, but is preferably just sufficient to dissolve the specified amount of photosensitizer. After incorporating the photosensitizer into the composition, the diluent may be removed, if desired, before irradiation of the composition. Removal of the diluent prior to irradiation of the composition may be desirable if the diluent is an acid polymerizable or acid curable or solvent for acid polymerizable materials. When the acid-polymerizable or acid-curable material is monomeric or contains monomers, the sensitizer may be soluble in the material and no diluent may be required. be.
The amount of photosensitizer is not critical, but will usually range from 0.01 to 10.0 wt%, preferably from 0.5 to 5 wt%, based on the weight of acid polymerizable and/or acid curable material in the composition. .0
It becomes Wt%.

Although increasing the amount of photosensitizer generally increases the rate of polymerization or curing achieved, there is usually little advantage in using amounts greater than 10 wt%. The photosensitizer should preferably be soluble in the resin in which it is formulated, with the solubility of the individual photosensitizer in the resin limiting the amount of the salt (photosensitizer) that can be incorporated. The polymerization or curing reaction initiated by irradiation of the composition is exothermic and the use of too much photomultiplier can cause the temperature to rise rapidly and the reaction conditions to be uncontrollable. .
The optimum amount of photosensitizer will usually be about 3-5 Wt%, but this will depend on the particular salt and acid polymerizable or acid curable material used and the radiation source, and will depend on simple experimentation.・It can be determined accordingly. Generally, when a composition is irradiated at room temperature, polymerization or curing of the composition easily proceeds, but the reaction is exothermic and may be accompanied by an increase in the temperature of the composition.

Irradiating the composition at elevated temperatures generally increases the rate of polymerization or curing. The compositions of the present invention can be used in any application in which acid-curable resin compositions are normally employed, provided that irradiation of the composition is possible when the composition is to be polymerized or cured in situ. can also be used.

The compositions of the invention can therefore be used, for example, to form surface coatings on various substrates (e.g. wood, paper, metal, textiles).
It can also be used in printing ink. In applications where the composition may be exposed to radiation in situ, the composition of the invention may be used as an adhesive. For example, it can be used as an adhesive in the manufacture of laminates where one or both laminates are radiation transparent (eg glass laminates and certain plastic laminates). Since the composition of the present invention has the property that only the area in contact with radiation is polymerized or hardened, the composition of the present invention can be cured by exposing a portion of its surface to radiation and then curing that portion. It can be used to make decorative articles with ringed surfaces by removing uncured material from the surface. The compositions according to the invention can therefore be used, for example, in the production of printing plates and printed circuits. The compositions of the present invention may include a blowing agent and may be foamed prior to irradiating the composition and then irradiating the composition to cure or set the foam. When the resin composition according to the invention is irradiated, polymerization or curing begins at the exposed surfaces and spreads towards the interior. The depth of cure achieved is limited by the depth of penetration of the composition by the radiation. This property can be utilized in the production of skinned materials such as skinned foams. Thus, for example, the foamable composition can be irradiated before foaming to form a thin skin layer of non-foaming hardened material, and the remaining composition can then be foamed to produce a foam with an integral skin. I can do it. One or more surfaces of the composition can be skinned in this manner.
Foams can be produced with a skinned surface with a ring. The compositions of the present invention may contain inert fillers and pigments so long as they do not interfere with the transmission of the composition by the radiation used to activate the photomultiplier. If desired, the composition may include one or more additional photosensitizers, such as radiation that will not activate the primary photosensitizer in the absence of the additional photosensitizer. This is to enable the composition to be activated. The present invention will be explained below with reference to Examples.

Example 1 [Ph3S4BF, θ; Ph = phenyl group] 0.3y of triphenylsulfonium tetrafluoropolite was dissolved in several ml of acetone, and the resulting solution was subjected to butylation of 2 parts in a solvent mixture. The mixture was mixed into 9.7 y of a urea/formaldehyde fat-alkyd resin mixture (solid content: 44 wt%) consisting of a mixture of the urea/formaldehyde resin and 3 parts of tall oil alkyd resin.

The resulting mixture was applied onto a steel plate and left to stand for a while to evaporate the solvent. This coated steel plate was then attached to two 2KW Phillips HTQ7 tubes positioned 8 inches apart.
Exposure to radiation from lamp tubes (known as HTQ light printing lamps). The spectral energy output of the lamp in mμ unit wavelength (energy %) was as follows: 248 (1.7), 254-2
58 (3.5), 265 (3.7), 270 (a). 7
), 275 (0.7), 280 (1.7), 289 (1
．． 0), 297 (3.0), 302 (4.7), 313
(12.1), 334 (1.4), 366 (20.6)
, 405 (6.1), 436 (12.4), 492 (0
．． 7), 546 (11.2), 578 (14.8). 1
After a few minutes had elapsed, the steel plate was taken out and observed, and it was found that the steel plate was coated with a very hard (pencil hardness: 611) solvent-resistant film.

Solvent resistance was determined by rubbing the film 20 times with a cloth soaked in acetone and examining the change in appearance (if any) caused by such treatment. In addition, in the above mixture in which triphenylsulfonium tetrafluoroporate was omitted, satisfactory curing was not achieved by irradiation.

Example 2 Using [Ph2(C2H-.)S(+)BF4○] diphenylethylsulfonium tetrafluorophorate,
Then, the irradiation was repeated for 2 minutes, and the procedure of Example 1 was repeated.

A solvent resistant film of pencil hardness was obtained. Example 3 [PH3SlSbCl6O] The procedure of Example 1 was repeated using triphenylsulfonium hexachloroantimonate in place of the triphenylsulfonium tetrafluoropolyte of Example 1.

After 1 minute of irradiation, a solvent-resistant film with a light pencil hardness was obtained.

Example 4 [Ph3SlPF6θ] Triphenylsulfonium hexafluorophosphate was used as a photomultiplier in an amount of 4% by weight (4% by weight based on the resin).
). The following resins were cured according to the procedure of Example 1 for the following exposure times using 08y photosensitizer dissolved in 0.5y acetone and mixed with 2y resin.

A satisfactory hard, solvent-resistant film was obtained in each experiment. --- Example 5 Triphenylsulfonium tetrafluoroborate (a). 02y) and N-vinylcarbazole (2.5y) in methylene chloride (3.5ml
) to make a solution.

In a glass bottle centered on eight 20W Phillips [Black Light] fluorescent tubes arranged in a circle (approximately 20 cm = 8 inches in diameter) and surrounded by a cylindrical reflector of polished metal plate. The above solution was irradiated. After about 2 minutes an exothermic reaction occurred, accompanied by a color change and fluorescence, and after 2 minutes the solution became viscous as a result of polymerization of the N-vinylcarbazole.

Example 6 (Storage test) Diphenylethylsulfonium tetrafluoroborate (a). 3y) in several ml of acetone, and this solution was mixed with 9.7 g of methylated melamine/formaldehyde resin (Ciba Geigy's "Cibami 7 ■ 000CB":
Trademark).

This mixture was stored in a black bottle in a dark cupboard at room temperature. After 12 months, the mixture showed no significant signs of gelling and, upon irradiation, had hardened as if it had been freshly prepared.

Claims (1)

[Scope of Claims] 1 (a) a substance selected from the group consisting of formaldehyde condensates of urea, melamine and phenol; and N-vinylcarbazole; (b) at least one photosensitizer; and whose photosensitizer is capable of polymerizing or curing said (a) substance when the composition is exposed to radiation of a wavelength that activates it. Composition: The photosensitizer has the following formula (I) ▲ Numerical formula, chemical formula, table, etc. ▼ (I) (In the formula, A is sulfur, selenium or tellurium, and n is 1 or 2, and R_1, R_2 and R_3 may be the same or different, each being a hydrocarbon group, a substituted hydrocarbon group or a heterocyclic group; or two of R_1, R_2 and R_3 and an element A and A together form a heterocyclic structure, one other group R is a hydrocarbon group or a substituted hydrocarbon group, and X is derived from an acid capable of polymerizing or curing the substance (a) above. The above-mentioned photopolymerizable composition is at least one salt having an anion.